JP2006248506A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact steering device capable of surely turning a pair of wheels, in regard to a steering device for separately turning each of a pair of wheels. <P>SOLUTION: In this steering device for steering a pair of wheels 58, a first motor 34a is operated in response to steering operation of a steering wheel 12. A first rack shaft 52 turns one of the wheels. A ball screw mechanism converts the low-torque rotating movement of a first rotor 31a to the high-thrust axial directional movement of the first rack shaft 52. A second motor 34b is operated in response to steering operation of the steering wheel 12. A second rack shaft 53 separated from the first rack shaft 52 turns the other wheel 58. The ball screw mechanism converts the low-torque rotating movement of a second rotor 31b to the high-thrust axial directional movement of the second rack shaft 53. A lock mechanism 60 connects the first rotor 31a and the second rotor 31b to each other, and separates them from each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steering device, and relates to a steering device that steers a pair of wheels in accordance with a steering operation of a steering wheel.

A vehicle steering apparatus generally includes a rack that is mechanically coupled to left and right wheels via tie rods, knuckle arms, and the like. When the steering wheel is rotated by the driver, the rack is moved in the axial direction, and the left and right wheels are steered integrally.
In recent years, a technique has been proposed in which the mechanical connection between the left and right wheels is separated and the steering of the left and right wheels is independently controlled and adjusted. For example, in Patent Document 1, a vehicle steering system is provided that includes a steering actuator attached to each of a plurality of wheels and a link member that links the plurality of wheels to each other, and independently controls the steering of the left and right wheels. A device has been proposed. Further, in Patent Document 2, for example, a vehicle that performs expansion and contraction by itself by a nut portion and a screw portion provided between a rack and a wheel that moves in the lateral direction of the vehicle according to a steering operation, and changes the angle of the wheel. A steering angle variable device has been proposed. By adopting such a steering device, it becomes possible to perform steering control / adjustment according to traveling conditions such as turning speed.
JP 2003-170849 A Japanese Patent Laid-Open No. 10-324253

  Thus, in a steering device that independently steers the left and right wheels, the left and right wheels can be steered stably even when a failure occurs in the actuator for steering one of the wheels. Desired. On the other hand, Patent Document 2 does not describe any technique for reliably turning a pair of wheels when a failure occurs in an actuator for turning the wheels. In the vehicle steering apparatus described in Patent Document 1, when one steering actuator falls into a failure state, the operation of the other steering actuator is transmitted via the link member, and the left and right wheels are steered. However, in the vehicle steering apparatus described in Patent Document 1, a load for the link member to link a plurality of wheels to each other is large, and a large link member must be provided to cope with such a large load.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a compact steering device that can reliably steer a pair of wheels in a steering device that steers each pair of wheels independently. Is to provide.

  In order to solve the above-described problem, a steering apparatus according to an aspect of the present invention includes a first motor that operates in accordance with a steering operation of a steering handle in a steering apparatus that steers a pair of wheels in response to a steering operation of a steering handle. The low-torque rotational motion of the first steering shaft that steers one of the pair of wheels and the first rotor, which is the rotational element of the first motor, is converted into high thrust axial motion of the first steering shaft. A first conversion mechanism that converts, a second motor that operates in response to a steering operation of the steering wheel, and a second steering shaft that is separated from the first steering shaft and that steers the other of the pair of wheels; A second conversion mechanism that converts a low-torque rotational motion of the second rotor, which is a rotational element of the second motor, into a high-thrust axial motion of the second steering shaft; and a first rotor and a second rotor connected to each other. And connecting means for releasing the connection. According to this aspect, the low-torque first rotor and the second rotor can be connected to each other, and the connection can be released. For this reason, when a failure occurs in one of the first motor and the second motor, the first steering shaft and the second steering shaft can be interlocked by connecting the first rotor and the second rotor with a low load. it can. Therefore, when connecting the first rotor and the second rotor, the connecting means can be configured in a compact manner, and a compact steering device capable of reliably turning a pair of wheels can be provided.

  The connecting means may include differential means for giving a differential to the first rotor and the second rotor, and a lock means for locking the differential means. According to this aspect, the first rotor and the second rotor can be connected to each other by locking the differential between the first rotor and the second rotor, and the first lock can be achieved by releasing the differential lock. The connection between the rotor and the second rotor can be released. For this reason, it becomes possible to connect a 1st rotor and a 2nd rotor with a low load by a differential means. Therefore, a compact differential means can be used, and the entire steering apparatus can be miniaturized.

  The differential means meshes with a rotatable first sun gear coupled to the first rotor, a first internal gear that can rotate coaxially with the first sun gear, and the first sun gear and the first internal gear. A first planetary gear, a rotatable second sun gear coupled to the second rotor, a second internal gear arranged coaxially with the second sun gear and restricted in rotation, and a second sun gear And a second planetary gear mechanism that meshes with the second internal gear and has a second planetary gear that is coaxially connected to the first planetary gear and rotatably connected to each other. The lock means may restrict the differential by the differential means by restricting the rotation of the first internal gear. According to this aspect, the differential mechanism can be easily configured by using the planetary gear mechanism.

  The differential means may have a third motor that drives the first internal gear. According to this aspect, since not only the first motor and the second motor but also the third motor can be used for left and right independent steering control, the load on the first motor and the second motor can be reduced.

  Provided between the first internal gear and the third motor. When torque is applied from the third motor side, torque is transmitted to the first internal gear and torque is applied from the first internal gear side. In this case, the lock means may have torque transmitting means for interrupting the torque to the third motor and locking the drive of the first internal gear. According to this aspect, if the third motor is driven, a differential can be given to the first rotor and the second rotor, and if the third motor is not driven, the first rotor and the second rotor can be connected. . For this reason, when connecting a 1st rotor and a 2nd rotor, it can suppress that a malfunction arises in a locking means, and can improve the reliability of a steering device.

  You may further provide the motor abnormality detection means which detects abnormality of a 1st motor and a 2nd motor. When no abnormality is detected in the first motor and the second motor, the connecting means releases the connection between the first rotor and the second rotor, and when an abnormality is detected in at least one of the first motor and the second motor. The first rotor and the second rotor may be connected to each other. According to this aspect, even when an abnormality occurs in any of the motors, the wheels can be appropriately steered.

  When an abnormality is detected in one of the first motor and the second motor by the motor abnormality detection means, the other may be operated in accordance with the steering operation of the steering wheel. According to this aspect, even when one of the first motor and the second motor is abnormal, the driver can assist the steering operation by operating the other motor.

  The steering apparatus according to this aspect may further include a rotation angle detection unit that detects a rotation angle difference between the first motor and the second motor, and before the first rotor and the second rotor are coupled by the coupling unit. The third motor may be operated so that the rotation angle difference detected by the rotation angle detection means is eliminated. According to this aspect, even when an abnormality occurs in either the first motor or the second motor, the first rotor and the second rotor are connected with the rotational angle difference between the first rotor and the second rotor eliminated. Can be linked. Therefore, it is possible to realize steering at an appropriate angle between the left and right wheels.

  The steering device of this aspect includes an input shaft coupled to the steering handle, an output shaft coupled to one of the first steering shaft or the second steering shaft via a steering gear, a differential mechanism, and a motor, You may further provide the transmission ratio variable means which operates a differential mechanism by operating a motor, and makes variable the transmission ratio between an input shaft and an output shaft. According to this aspect, it is possible to provide mechanical connection from the steering handle to one of the first steering shaft and the second steering shaft via the input shaft and the output shaft. For this reason, the steering shaft having a mechanical connection can be reliably steered, and the left and right wheels can be reliably steered by connecting the first steering shaft and the second steering shaft.

  According to the steering device of the present invention, it is possible to provide a compact steering device that can reliably steer a pair of wheels in a steering device that independently steers each of a pair of wheels.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an overall configuration diagram of a steering apparatus 200 according to the first embodiment. This figure has shown the state seen from the vehicle rear toward the front. The steering device 200 includes a steering handle 12 operated by a driver, a steering shaft 14 connected to the steering handle 12, and a steering mechanism 50 provided at the lower end of the steering shaft 14. A pinion gear 22 is attached to the lower end of the steering shaft 14, and the pinion gear 22 is meshed with rack teeth 52b of a first rack shaft 52 supported in the steering mechanism 50 so as to be movable in the vehicle width direction. Configure the and pinion mechanism.

  One end of a tie rod 54 is connected to the end of the first rack shaft 52. The other end of the tie rod 54 is connected to a knuckle arm 56 that supports the right wheel 58. The knuckle arm 56 rotates using a king pin (not shown) as a fulcrum. When the steering handle 12 is operated and the steering shaft 14 is rotated, this rotation is converted into a linear motion in the left-right direction of the vehicle by the steering mechanism 50. This linear motion is converted into rotation around the kingpin of the knuckle arm 56, and the right wheel 58 is steered.

  The steering shaft 14 is divided into an input shaft 14 a connected to the steering handle 12 and an output shaft 14 b connected to the steering mechanism 50. The output shaft 14b and the input shaft 14a are connected via a transmission ratio variable device 20.

  The transmission ratio variable device 20 is a device having a function of improving the steering operability regardless of the vehicle speed by controlling the transmission characteristics between the steering handle 12 and the wheels 58 based on information such as the vehicle speed and the steering angle. It is. The transmission ratio variable device 20 includes a speed reduction mechanism 20a, a motor (not shown), a lock mechanism that directly connects the input shaft 14a and the output shaft 14b, and the like. The rotation of the steering handle 12 is transmitted to the motor housing of the transmission ratio variable device 20 through the input shaft 14a.

  The speed reduction mechanism 20a of the transmission ratio variable device 20 is configured as a differential generation mechanism. The differential generation mechanism rotates a cam of a wave generator fixed to the rotation shaft of the motor by driving the motor, and causes a rotation difference between the stator gear and the driven gear via the flexible gear. By extracting this rotational difference and adding it to the rotation of the stator gear itself transmitted from the input shaft 14a, a steering angle larger than the steering angle of the steering handle 12 can be generated on the output shaft 14b.

  Further, the transmission ratio variable device 20 is provided with a lock mechanism 20b. The lock mechanism 20b operates the solenoid to engage the lock pin with the groove, thereby disabling the rotation of the output shaft 14b with respect to the input shaft 14a, thereby rotating the transmission ratio variable device 20 as a whole. . The motor of the transmission ratio variable device 20 is provided with a rotation sensor (not shown), and this rotation sensor is connected to an electronic control unit 100 (hereinafter referred to as “ECU 100”) that is a control means of the steering device 200. Has been. The ECU 100 determines whether an abnormality has occurred in the transmission ratio variable device 20 based on the detection result of the rotation sensor. If an abnormality has occurred in the transmission ratio variable device 20, the ECU 100 operates the lock mechanism 20b. By inputting the signal, the transmission ratio variable device 20 is integrally rotated, and the steering with the transmission ratio fixed from the steering handle 12 to the wheel 58 becomes possible. Thereby, the influence which abnormality of the transmission ratio variable apparatus 20 has on driving | running | working of a vehicle becomes the minimum.

  The input shaft 14a is provided with a steering angle sensor 16 that detects the steering angle and the steering direction of the steering handle 12 by detecting the rotation angle of the input shaft 14a. The input shaft 14a is provided with a steering torque sensor 18 that detects a steering torque applied to the steering handle 12. The steering angle, steering direction, and steering torque of the steering handle 12 detected by the steering angle sensor 16 and the steering torque sensor 18 are input to the ECU 100.

  The steering mechanism 50 includes a first rack shaft 52 that steers wheels on the right side of the vehicle, a second rack shaft 53 that steers wheels on the left side of the vehicle, a first motor 34 a that drives the first rack shaft 52, and a second A second motor 34b for driving the rack shaft 53, a differential mechanism 40 provided between the first motor 34a and the second motor 34b, and the like are configured.

  The first motor 34 a includes a first stator 30 a fixed to the rack housing 51, a first rotor 31 a that is rotatably supported by the rack housing 51 via a bearing 32, and the like. The first rotor 31 a is formed in a cylindrical shape and includes one end portion of the first rack shaft 52. A screw portion is formed on the inner peripheral portion of the first rotor 31a, and constitutes a ball screw nut. On the other hand, a threaded groove-shaped first rolling path 52a is formed on the outer periphery of one end of the first rack shaft 52, and a plurality of rolling balls 33 are formed on the first rolling path 52a. It is fitted to roll freely. Thus, the ball screw mechanism is configured by connecting the screw portion of the inner peripheral portion of the first rotor 31 a and the first rolling path 52 a via the rolling ball 33.

  When the first rotor 31a rotates by driving the first motor 34a, the rotational torque of the first rotor 31a is passed through the plurality of rolling balls 33 rolling on the first rolling path 52a by the above-described ball screw mechanism. This is converted into an axial thrust of the first rack shaft 52, whereby the first rack shaft 52 moves in the axial direction. Therefore, the ball screw mechanism functions as a conversion mechanism that converts the low-torque rotational motion of the first motor 34 a into the high-thrust axial motion of the first rack shaft 52. Of course, other screw mechanisms such as a screw mechanism without the rolling ball 33 may be employed instead of the ball screw mechanism.

  The ECU 100 calculates the assist torque for turning the wheel 58 on the right side of the vehicle based on the detection results of the steering torque sensor 18 and the vehicle speed sensor 24, and generates the drive torque corresponding to the assist torque. The drive of the motor 34a is controlled. Thus, the first motor 34a is driven, and the first rack shaft 52 moves in the axial direction, thereby assisting the steering operation of the steering handle 12 by the driver for turning the wheel 58 on the right side of the vehicle.

  The second motor 34b also includes a second stator 30b fixed to the rack housing 51, a second rotor 31b rotatably supported on the rack housing 51 via a bearing 32, and the like. Similarly to the first motor 34a, when the second rotor 31b rotates by driving the second motor 34b, the rotational torque of the second motor 34b rolls on the second rolling path 53a by the same ball screw mechanism as described above. The second rack shaft 53 is moved in the axial direction by being converted into an axial thrust force of the second rack shaft 53 via the plurality of rolling balls 33. Therefore, this ball screw mechanism also functions as a conversion mechanism that converts the low-torque rotational motion of the second motor 34 b into high-thrust axial motion of the second rack shaft 53. Of course, other screw mechanisms such as a screw mechanism without the rolling ball 33 may be employed instead of the ball screw mechanism.

  Similarly to the first rack shaft 52, one end of the tie rod 54 is connected to the end of the second rack shaft 53, and the other end of the tie rod 54 is connected to a knuckle arm 56 that supports the left wheel 58. As a result, the second rack shaft 53 is driven in the axial direction, whereby the wheel 58 on the left side of the vehicle is steered.

  The ECU 100 calculates the angle at which the wheel 58 on the left side of the vehicle is steered based on the detection result by the steering angle sensor 16, and the second motor 34b moves the second rack shaft by a length corresponding to this angle. Control the drive. In this way, the second motor 34b is driven and the first rack shaft 52 moves in the axial direction, whereby independent steering control of the wheel 58 on the left side of the vehicle is realized.

  Each of the first motor 34a and the second motor 34b is provided with a rotation sensor (not shown). The detection result of the rotation sensor is input to the ECU 100, and the ECU 100 determines the number of rotations of the first motor 34a and the second motor 34b and the occurrence of an abnormality based on the detection result of the rotation sensor.

  A differential mechanism 40 is provided between the first motor 34a and the second motor 34b. The differential mechanism 40 includes two sets of planetary gear mechanisms, and includes a first sun gear 41a, a first planetary gear 42a, a first internal gear 43a, a second sun gear 41b, a second planetary gear 42b, It is comprised by 2 internal gear 43b, the support plate 46, etc.

  The first sun gear 41a, the second sun gear 41b, and the first internal gear 43a are supported on the rack housing 51 so as to be coaxial and rotatable with the first rotor 31a and the second rotor 31b.

  A first sun gear 41a is connected to the end of the first rotor 31a via a first transmission shaft 45a. A first internal gear 43a is provided on the radially outer side of the first sun gear 41a, and the first planetary gear 42a meshes with the external teeth of the first sun gear 41a and the internal teeth of the first internal gear 43a. is doing. The first internal gear 43 a is supported by the bearing 44 so as to be rotatable with respect to the rack housing 51. A second sun gear 41b is connected to the end of the second rotor 31b via a second transmission shaft 45b. A second internal gear 43b is provided on the radially outer side of the second sun gear 41b, and the second planetary gear 42b meshes with the external teeth of the second sun gear 41b and the internal teeth of the second internal gear 43b. is doing. The outer periphery of the second internal gear 43 b is fixed to the rack housing 51, and the second internal gear 43 b is not rotatable with respect to the rack housing 51.

  The first planetary gears 42a are connected to the corresponding second planetary gears 42b by third transmission shafts 47 so as to be mutually rotatable via bearings (not shown). These third transmission shafts 47 are inserted through the through holes of the support plate 46 and are supported in a state where the mutual movement of the three third transmission shafts 47 is restricted.

  The first sun gear 41a and the second sun gear 41b have the same gear specifications such as the pitch circle radius, pitch, and number of teeth of the outer peripheral gear portion. Similarly, the first planetary gear 42a and the second planetary gear 42b, and the first internal gear 43a and the second internal gear 43b all have the same gear specifications.

  A lock mechanism 60 that locks the differential of the differential mechanism 40 is provided inside the rack housing 51 and in the vicinity of the differential mechanism 40. The lock mechanism 60 is fixed to the rack housing 51 and moves the lock pin forward and backward by a solenoid or a return spring (not shown) toward a groove provided in the first internal gear 43a. By engaging the lock pin with the groove in this way, the first internal gear 43a is fixed to the rack housing 51, and the rotation is restricted.

  With the above configuration, when the lock by the lock mechanism 60 is released and the first internal gear 43a is rotatable, the first internal gear 43a is rotated, so that the first rotor 31a and the first A differential can be generated between the two rotors 31b. When the rotation of the first internal gear 43a is restricted by the lock mechanism 60, the differential provided to the first rotor 31a and the second rotor 31b by the differential mechanism 40 is restricted. In this case, since the specifications of the gears of the planetary gear mechanism on the first rotor 31a side and the planetary gear mechanism on the second rotor 31b side are the same, the rotation of the first sun gear 41a is input and the second sun gear is input. When the rotation of 41b is used as an output, the input: output is 1: 1. Therefore, the first rotor 31 a and the second rotor 31 b are coupled via the differential mechanism 40.

  The shape of the ball screw nut part formed in the internal diameter and the inner peripheral part of the 1st rotor 31a is the same as the 2nd rotor 31b. Further, the outer diameter of the first rack shaft 52 and the shape of the first rolling path 52a formed on the outer peripheral portion are the same as the outer diameter of the second rack shaft 53 and the shape of the second rolling path 53a. . Therefore, when the first rotor 31a and the second rotor 31b are connected to each other via the differential mechanism 40 and rotate, the first rack shaft 52 and the second rack shaft 53 have the same length in the same direction. Just move.

  When the ECU 100 determines that one or both of the first motor 34a and the second motor 34b are abnormal based on the detection results of the rotation sensors provided in the first motor 34a and the second motor 34b. Turns off the solenoid of the lock mechanism 60 and locks the differential of the differential mechanism 40 by a return spring. Accordingly, the first rotor 31a and the second rotor 31b are coupled via the differential mechanism 40, and the first rack shaft 52 and the second rack shaft 53 move by the same length in the same direction. As a result, even when an abnormality occurs in one or both of the first motor 34a and the second motor 34b, the wheel can be steered appropriately.

  Further, when the ECU 100 determines that one of the first motor 34a and the second motor 34b is abnormal, the lock mechanism 60 locks the differential of the differential mechanism 40 as described above, and the abnormality is detected. The other motor, which is determined not to be operated, is operated to assist the steering operation. Thereby, even if it is recognized that either one of the first motor 34a and the second motor 34b is abnormal, the driver's steering operation can be assisted.

  FIG. 2 is a flowchart for explaining a control procedure of the steering device 200 according to the first embodiment. The processing in this flowchart is repeatedly executed every predetermined time.

  The ECU 100 determines whether or not there is an abnormality in the first motor 34a based on the detection result of the rotation sensor provided in the first motor 34a (S11). When there is no abnormality in the first motor 34a (Y in S11), the ECU 100 determines whether there is an abnormality in the second motor 34b based on the detection result of the rotation sensor provided in the second motor 34b ( S12).

  When it is determined that there is no abnormality in both the first motor 34a and the second motor 34b (Y in S12), the ECU 100 inputs an independent operation signal to each of the first motor 34a and the second motor 34b. Independent steering control of the left and right wheels is performed (S13). Thereby, the operation performance of the vehicle can be improved. At this time, the differential between the first rack shaft 52 and the second rack shaft 53 is absorbed by the differential mechanism 40.

  When it is determined that there is no abnormality in the first motor 34a and there is an abnormality in the second motor 34b (N in S12), the ECU 100 inputs a predetermined operation signal to the solenoid of the lock mechanism 60 to obtain a differential. The differential of the mechanism 40 is locked (S14). Next, the ECU 100 stops the driving of the second motor 34b determined to be abnormal (S15), and executes the assist of the steering operation of the steering handle 12 only with the first motor 34a (S16).

  When there is an abnormality in the first motor 34a (N in S11), the ECU 100 locks the differential of the differential mechanism 40 by inputting a predetermined operation signal to the solenoid of the lock mechanism 60 (S17). Next, the ECU 100 determines whether there is an abnormality in the second motor 34b based on the detection result of the rotation sensor provided in the second motor 34b (S18).

  When it is determined that there is no abnormality in the second motor 34b (Y in S18), the ECU 100 stops the driving of the first motor 34a that is determined to be abnormal (S19), and is steered only by the second motor 34b. Assisting the steering operation of the handle 12 is executed (S20).

  If it is determined that the second motor 34b is also abnormal (N in S18), the ECU 100 stops driving the first motor 34a and the second motor 34b that are determined to be abnormal (S21). Accordingly, even when the first motor 34a and the second motor 34b that steer the left and right wheels are abnormal, the left and right wheels 58 can be appropriately steered.

(Second Embodiment)
FIG. 3 is an overall configuration diagram of the steering device 200 according to the second embodiment. The steering mechanism 50 according to the present embodiment includes a differential mechanism 40 having a first motor 34a, a second motor 34b, and a planetary gear mechanism provided between the first motor 34a and the second motor 34b. This is the same as the first embodiment.

  In the present embodiment, a gear 72, a third motor 71, and a reverse input blocking mechanism 70 are provided instead of the lock mechanism 60 in the first embodiment. The third motor 71 is fixed to the rack housing 51. The gear 72 meshes with a gear portion fixed to the first internal gear 43a. The third motor 71 and the gear 72 are connected via a reverse input blocking mechanism 70.

  The reverse input blocking mechanism 70 transmits the torque to the output shaft when torque is applied from the input shaft, but does not transmit the torque to the input shaft when torque is applied from the output shaft. A lock type that regulates rotation is adopted. In the present embodiment, the reverse input blocking mechanism 70 transmits the torque to the gear 72 when torque is applied from the third motor 71. However, when the torque is applied from the gear 72, the reverse input blocking mechanism 70 transmits the torque to the gear 72. The rotation of the gear 72 is restricted without being transmitted to the motor 71. Thereby, if it is desired to generate a differential between the first rotor 31a and the second rotor 31b, the third motor 71 may be driven, and if the third motor 71 is not driven, the reverse input is cut off. Since the 1st rotor 31a and the 2nd rotor 31b can be connected via the mechanism 70, steering can be performed appropriately and reliability can be improved.

  When the ECU 100 determines that there is no abnormality in any of the motors based on the detection results of the rotation sensors provided in each of the first motor 34a, the second motor 34b, and the third motor 71, the first motor 34a An independent operation signal is input to each of 34a and the second motor 34b to perform independent steering control of the left and right wheels. In the present embodiment, if the third motor 71 is not driven, no differential is generated between the first rotor 31a and the second rotor 31b. Therefore, the ECU 100 does not change between the first rotor 31a and the second rotor 31b. The differential to be given in between is calculated, and the third motor 71 is driven so as to generate the differential. As a result, not only the first motor 34a and the second motor 34b but also the third motor 71 can be used for left and right independent steering control, so that the load on each motor can be reduced.

  FIG. 4 is a flowchart for explaining a control procedure of the steering device 200 according to the second embodiment. The processing in this flowchart is repeatedly executed every predetermined time.

  The ECU 100 determines whether or not there is an abnormality in the third motor 71 based on the detection result of the rotation sensor provided in the third motor 71 (S31). When it is determined that there is an abnormality in the third motor 71, the process of FIG. 5 described later is executed (N in S31).

  If it is determined that there is no abnormality in the third motor 71 (Y in S31), the ECU 100 determines whether there is no abnormality in the first motor 34a based on the detection result of the rotation sensor provided in the first motor 34a. Is determined (S32). When there is no abnormality in the first motor 34a (Y in S32), the ECU 100 determines whether there is an abnormality in the second motor 34b based on the detection result of the rotation sensor provided in the second motor 34b ( S33).

  When it is determined that there is no abnormality in both the first motor 34a and the second motor 34b (Y in S33), the ECU 100 inputs an independent operation signal to each of the first motor 34a and the second motor 34b. In addition, an operation signal for applying a differential to the differential mechanism 40 is input to the third motor 71, and independent steering control of the left and right wheels is performed (S34). When it is determined that the first motor 34a is normal and the second motor 34b is abnormal (N in S33), the ECU 100 locks the differential between the first rotor 31a and the second rotor 31b. Therefore, the driving of the third motor is stopped (S35), the driving of the second motor 34b determined to be abnormal is stopped (S36), and then the ECU 100 determines that there is no abnormality. The assist of the steering operation of the steering handle 12 is executed by the 1 motor 34a (S37).

If it is determined that there is an abnormality in the first motor 34a (N in S32), the ECU 100 drives the third motor to lock the differential between the first rotor 31a and the second rotor 31b. Stop (S38). Next, the ECU 100 determines whether there is an abnormality in the second motor 34b based on the detection result of the rotation sensor provided in the second motor 34b (S39).
If it is determined that there is no abnormality in the second motor 34b (Y in S39), the ECU 100 stops the driving of the first motor 34a that is determined to be abnormal (S40), and it is determined that there is no abnormality. The second motor 34b assists the steering operation of the steering handle 12 (S41). If it is determined that the second motor 34b is also abnormal (N in S39), the ECU 100 stops driving the first motor 34a and the second motor 34b that are determined to be abnormal (S42).

  Note that the ECU 100 detects the first rotor 31a and the first rotor 31a detected by the rotation sensors provided in the first motor 34a and the second motor 34b before locking the differential between the first rotor 31a and the second rotor 31b. The rotation angle difference between the two rotors 31b is calculated, and the third motor 71 is operated so that the rotation angle difference between the first rotor 31a and the second rotor 31b is eliminated. As a result, even when an abnormality occurs in either the first motor 34a or the second motor 34b, the differential between the first rotor 31a and the second rotor 31b is locked in a state where the rotational angle difference between the first rotor 31a and the second rotor 31b is eliminated. Can do.

  FIG. 5 is a flowchart for explaining a control procedure when there is an abnormality in the third motor of the steering device 200 according to the second embodiment. The processing in this flowchart is repeatedly executed every predetermined time.

  When it is determined that the third motor 71 is abnormal (N in S31 of FIG. 4), the ECU 100 stops the driving of the third motor 71 determined to be abnormal (S51). Accordingly, the differential between the first rotor 31a and the second rotor 31b is regulated by the lock-type reverse input blocking mechanism 70.

  Next, the ECU 100 determines whether or not there is an abnormality in the first motor 34a based on the detection result of the rotation sensor provided in the first motor 34a (S52). Regardless of whether the first motor 34a is normal (Y in S52) or abnormal (N in S52), the ECU 100 determines the second based on the detection result of the rotation sensor provided in the second motor 34b. It is determined whether or not there is an abnormality in the motor 34b (S53, S57).

  When it is determined that there is no abnormality in both the first motor 34a and the second motor 34b (Y in S53), the ECU 100 inputs the same operation signal to each of the first motor 34a and the second motor 34b. The first motor 34a and the second motor 34b are used to assist the steering operation of the steering handle 12 (S54).

  When it is determined that there is no abnormality in the first motor 34a and there is an abnormality in the second motor 34b (N in S53), the ECU 100 stops driving the second motor 34b that is determined to be abnormal (N). S55). Next, the ECU 100 causes the steering operation of the steering handle 12 to be assisted by the first motor 34a determined to be normal (S56).

  When it is determined that there is an abnormality in the first motor 34a and there is no abnormality in the second motor 34b (Y in S57), the ECU 100 stops the driving of the first motor 34a that is determined to be abnormal (Y). S58). Next, the ECU 100 causes the steering operation of the steering handle 12 to be assisted by the second motor 34b determined to be normal (S59).

  When it is determined that both the first motor 34a and the second motor 34b are abnormal (N in S57), the ECU 100 stops driving the first motor 34a and the second motor 34b that are determined to be abnormal. (S60).

(Third embodiment)
FIG. 6 is an overall configuration diagram of the steering device 200 according to the third embodiment. In the present embodiment, the differential mechanism 40 and the like in the above-described embodiment are not provided, and a clutch 80 is provided.

  The clutch 80 is constituted by an electromagnetic clutch, and connects the first rotor 31a and the second rotor 31b when energized. The ECU 100 connects the first rotor 31a and the second rotor 31b by inputting a connection signal to the clutch 80, and releases the connection by stopping the input of the connection signal. Thereby, the 1st rotor 31a and the 2nd rotor 31b can be connected by simple structure, without providing the differential mechanism 40 grade | etc.,. Note that the control procedure in the present embodiment is obtained by replacing the differential regulation between the rotors with the coupling by the clutch 80 between the rotors in FIG.

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention. Here are some examples.

  The transmission ratio variable device 20 may be omitted. In this case, since the input shaft 14a and the output shaft 14b of the steering shaft 14 are coupled, the first rack shaft 52 can be directly moved by operating the steering handle 12.

1 is an overall configuration diagram of a steering apparatus according to a first embodiment. It is a flowchart for demonstrating the control procedure of the steering device concerning 1st Embodiment. It is a whole block diagram of the steering device concerning 2nd Embodiment. It is a flowchart for demonstrating the control procedure of the steering device concerning 2nd Embodiment. It is a flowchart for demonstrating the control procedure when there is abnormality in the 3rd motor of the steering device concerning 2nd Embodiment. It is a whole block diagram of the steering device concerning 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 Steering handle, 14 Steering shaft, 16 Steering angle sensor, 18 Steering torque sensor, 20 Transmission ratio variable device, 22 Pinion gear, 24 Vehicle speed sensor, 31a 1st rotor, 31b 2nd rotor, 34a 1st motor, 34b 2nd motor , 40 differential mechanism, 50 steering mechanism, 52 first rack shaft, 53 second rack shaft, 58 wheels, 60 locking mechanism, 70 reverse input blocking mechanism, 71 third motor, 100 electronic control unit.

Claims (9)

In a steering device that steers a pair of wheels according to a steering operation of a steering handle,
A first motor that operates in response to a steering operation of the steering wheel;
A first steering shaft that steers one of the pair of wheels;
A first conversion mechanism that converts a low-torque rotational motion of a first rotor, which is a rotational element of the first motor, into a high-thrust axial motion of the first steering shaft;
A second motor that operates in response to a steering operation of the steering wheel;
A second steering shaft that is separated from the first steering shaft and steers the other of the pair of wheels;
A second conversion mechanism for converting a low-torque rotational motion of a second rotor, which is a rotational element of the second motor, into a high-thrust axial motion of the second steering shaft;
Connecting means for connecting the first rotor and the second rotor and releasing the connection;
A steering apparatus comprising:   The said connection means has the differential means which gives a differential mutually to the said 1st rotor and the said 2nd rotor, and the locking means which locks this differential means, The Claim 1 characterized by the above-mentioned. Steering device. The differential means includes a rotatable first sun gear coupled to the first rotor, a first internal gear rotatable coaxially with the first sun gear, the first sun gear and the first inner gear. A first planetary gear meshing with a toothed gear, a rotatable second sun gear coupled to the second rotor, and a second internal gear arranged coaxially with the second sun gear and restricted in rotation. A planetary gear mechanism having a second planetary gear meshing with the second sun gear and the second internal gear and coaxially coupled to the first planetary gear and rotatably connected to each other,
The steering apparatus according to claim 2, wherein the locking means locks the differential means by restricting rotation of the first internal gear.   The steering apparatus according to claim 3, wherein the differential unit includes a third motor that drives the first internal gear.   The locking means is provided between the first internal gear and the third motor. When torque is applied from the third motor, the lock means transmits the torque to the internal gear, and the second gear 5. The apparatus according to claim 4, further comprising torque transmitting means for restricting the rotation of the second internal gear by interrupting the torque to the third motor when torque is applied from the internal gear. The steering apparatus described. Motor abnormality detecting means for detecting abnormality of the first motor and the second motor;
The connecting means releases the connection between the first rotor and the second rotor when no abnormality is detected in the first motor and the second motor by the motor abnormality detecting means, and the motor abnormality detecting means The steering according to any one of claims 1 to 5, wherein the first rotor and the second rotor are connected when an abnormality is detected in at least one of the first motor and the second motor. apparatus.   When an abnormality is detected in one of the first motor and the second motor by the motor abnormality detecting means, the other of the first motor and the second motor is operated according to a steering operation of a steering wheel. The steering apparatus according to claim 6, wherein the steering apparatus is characterized. A rotation angle detecting means for detecting a rotation angle difference between the first motor and the second motor;
The third motor is operated so that the rotation angle difference detected by the rotation angle detecting means is eliminated before the first rotor and the second rotor are connected by the connecting means. Item 5. The steering device according to Item 4. An input shaft coupled to the steering handle;
An output shaft connected to one of the first steering shaft or the second steering shaft via a steering gear;
And a transmission ratio variable means that includes a differential mechanism and a motor, and operates the differential mechanism by operating the motor to vary a transmission ratio between the input shaft and the output shaft. The steering apparatus according to any one of claims 1 to 8, wherein the steering apparatus is characterized.

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